Сьюзан Кейн - Quiet [The Power of Introverts in a World That Can't Stop Talking]

The upsides of the high-reactive temperament have been documented in exciting research that scientists are only now beginning to pull together. One of the most interesting findings, also reported in Dobbs’s Atlantic article, comes from the world of rhesus monkeys, a species that shares about 95 percent of its DNA with humans and has elaborate social structures that resemble our own.

In these monkeys as well as in humans, a gene known as the serotonin-transporter (SERT) gene, or 5-HTTLPR, helps to regulate the processing of serotonin, a neurotransmitter that affects mood. A particular variation, or allele, of this gene, sometimes referred to as the “short” allele, is thought to be associated with high reactivity and introversion, as well as a heightened risk of depression in humans who have had difficult lives. When baby monkeys with a similar allele were subjected to stress—in one experiment they were taken from their mothers and raised as orphans—they processed serotonin less efficiently (a risk factor for depression and anxiety) than monkeys with the long allele who endured similar privations. But young monkeys with the same risky genetic profile who were raised by nurturing mothers did as well as or better than their long-allele brethren—even those raised in similarly secure environments—at key social tasks, like finding playmates, building alliances, and handling conflicts. They often became leaders of their troops. They also processed serotonin more efficiently.

Stephen Suomi, the scientist who conducted these studies, has speculated that these high-reactive monkeys owed their success to the enormous amounts of time they spent watching rather than participating in the group, absorbing on a deep level the laws of social dynamics. (This is a hypothesis that might ring true to parents whose high-reactive children hover observantly on the edges of their peer group, sometimes for weeks or months, before edging successfully inside.)

Studies in humans have found that adolescent girls with the short allele of the SERT gene are 20 percent more likely to be depressed than long-allele girls when exposed to stressful family environments, but 25 percent less likely to be depressed when raised in stable homes. Similarly, short allele adults have been shown to have more anxiety in the evening than others when they’ve had stressful days, but less anxiety on calm days. High-reactive four-year-olds give more pro-social responses than other children when presented with moral dilemmas—but this difference remains at age five only if their mothers used gentle, not harsh, discipline. High-reactive children raised in supportive environments are even more resistant than other kids to the common cold and other respiratory illnesses, but get sick more easily if they’re raised in stressful conditions. The short allele of the SERT gene is also associated with higher performance on a wide range of cognitive tasks.

These findings are so dramatic that it’s remarkable no one arrived at them until recently. Remarkable, but perhaps not surprising. Psychologists are trained to heal, so their research naturally focuses on problems and pathology. “It is almost as if, metaphorically speaking, sailors are so busy—and wisely—looking under the water line for extensions of icebergs that could sink their ship,” writes Belsky, “that they fail to appreciate that by climbing on top of the iceberg it might prove possible to chart a clear passage through the ice-laden sea.”

The parents of high-reactive children are exceedingly lucky, Belsky told me. “The time and effort they invest will actually make a difference. Instead of seeing these kids as vulnerable to adversity, parents should see them as malleable—for worse, but also for better.” He describes eloquently a high-reactive child’s ideal parent: someone who “can read your cues and respect your individuality; is warm and firm in placing demands on you without being harsh or hostile; promotes curiosity, academic achievement, delayed gratification, and self-control; and is not harsh, neglectful, or inconsistent.” This advice is terrific for all parents, of course, but it’s crucial for raising a high-reactive child. (If you think your child might be high-reactive, you’re probably already asking yourself what else you can do to cultivate your son or daughter. Chapter 11 has some answers.)

But even orchid children can withstand some adversity, Belsky says. Take divorce. In general, it will disrupt orchid kids more than others: “If the parents squabble a lot, and put their kid in the middle, then watch out—this is the kid who will succumb.” But if the divorcing parents get along, if they provide their child with the other psychological nutrients he needs, then even an orchid child can do just fine.

Most people would appreciate the flexibility of this message, I think; few of us had problem-free childhoods.

But there’s another kind of flexibility that we all hope applies to the question of who we are and what we become. We want the freedom to map our own destinies. We want to preserve the advantageous aspects of our temperaments and improve, or even discard, the ones we dislike—such as a horror of public speaking. In addition to our inborn temperaments, beyond the luck of the draw of our childhood experience, we want to believe that we—as adults—can shape our selves and make what we will of our lives.

Can we?

Deep inside the bowels of the Athinoula A. Martinos Center for Biomedical Imaging at Massachusetts General Hospital, the hallways are nondescript, dingy even. I’m standing outside the locked door of a windowless room with Dr. Carl Schwartz, the director of the Developmental Neuroimaging and Psychopathology Research Lab. Schwartz has bright, inquisitive eyes, graying brown hair, and a quietly enthusiastic manner. Despite our unprepossessing surroundings, he prepares with some fanfare to unlock the door.

The room houses a multimillion-dollar fMRI (functional magnetic resonance imaging) machine, which has made possible some of the greatest breakthroughs in modern neuroscience. An fMRI machine can measure which parts of the brain are active when you’re thinking a particular thought or performing a specific task, allowing scientists to perform the once unimaginable task of mapping the functions of the human brain. A principal inventor of the fMRI technique, says Dr. Schwartz, was a brilliant but unassuming scientist named Kenneth Kwong, who works inside this very building. This whole place is full of quiet and modest people doing extraordinary things, Schwartz adds, waving his hand appreciatively at the empty hallway.

Before Schwartz opens the door, he asks me to take off my gold hoop earrings and set aside the metal tape recorder I’ve been using to record our conversation. The magnetic field of the fMRI machine is 100,000 times stronger than the earth’s gravitational pull—so strong, Schwartz says, that it could rip the earrings right out of my ears if they were magnetic and send them flying across the room. I worry about the metal fasteners of my bra, but I’m too embarrassed to ask. I point instead to my shoe buckle, which I figure has the same amount of metal as the bra strap. Schwartz says it’s all right, and we enter the room.

We gaze reverently at the fMRI scanner, which looks like a gleaming rocketship lying on its side. Schwartz explains that he asks his subjects—who are in their late teens—to lie down with their heads in the scanner while they look at photographs of faces and the machine tracks how their brains respond. He’s especially interested in activity in the amygdala—the same powerful organ inside the brain that Kagan found played such an important role in shaping some introverts’ and extroverts’ personalities.